19762015
  • Authors:
    • Lal, R.
    • Blanco-Canqui, H.
  • Source: Soil Science Society of America Journal
  • Volume: 72
  • Issue: 3
  • Year: 2008
  • Summary: No-tillage (NT) farming is superior to intensive tillage for conserving soil and water, yet its potential for sequestering soil organic carbon (SOC) in all environments as well as its impacts on soil profile SOC distribution are not well understood. Thus, we assessed the impacts of long-term NT-based cropping systems on SOC sequestration for the whole soil profile (0-60-cm soil depth) across 11 Major Land Resource Areas (MLRAs: 121, 122, and 125 in Kentucky; 99, 124, 139A in Ohio; and 139B, 139C, 140, 147, and 148 in Pennsylvania) in the eastern United States. Soil was sampled in paired NT and plow tillage (PT) based cropping systems and an adjacent woodlot (WL). No-tillage farming impacts on SOC and N were soil specific. The SOC and N concentrations in NT soils were greater than those in PT soils in 5 out of 11 MLRAs (121, 122, 124, 139A, and 148), but only within the 0- to 10-cm depth. Below 10 cm, NT soils had lower SOC than PT soils in MLRA 124. The total SOC with NT for the whole soil profile (0-60 cm) did not differ from that with PT (P > 0.10) in accord with several previous studies. In fact, total soil profile SOC in PT soils was 50% higher in MLRA 125, 21% in MLRA 99, and 41% in MLRA 124 compared with that in NT soils. Overall, this study shows that NT farming increases SOC concentrations in the upper layers of some soils, but it does not store SOC more than PT soils for the whole soil profile.
  • Authors:
    • Pierzynski, G.
    • Tuppad, P.
    • Janssen, K.
    • Mankin, K.
    • Maski, D.
  • Source: Journal of Soil and Water Conservation
  • Volume: 63
  • Issue: 4
  • Year: 2008
  • Summary: Cropland best management practice recommendations often combine improvements to both tillage and fertilizer application practices to reduce sediment losses with surface runoff. This study evaluated the impact of conventional-till and no-till management practices with surface or deep-banded fertilizer application in sorghum-soybean rotation on runoff and sediment-yield predictions using the Soil and Water Assessment Tool (SWAT) model. The model was calibrated using USDA Natural Resources Conservation Service runoff curve number for antecedent moisture condition II (CN II), saturated hydraulic conductivity, and available water capacity parameters for runoff and USLE cropping factor ( Cmin.) for sediment-yield predictions for three field plots (0.39 to 1.46 ha [0.96 to 3.6 ac]) with different combinations of practices and validated for three field plots (0.40 to 0.56 ha [1.0 to 1.4 ac]) over a period of 2000 to 2004. Surface runoff calibration required CN II values greater than the recommended baseline values. No-till treatments required slightly greater curve number values than the till treatment, and this difference was similar to that associated with increasing the soil hydrologic group by one classification. Generally the model underpredicted the sediment yield for all management practices. Baseline Cmin values were adequate for treatments with soil disturbance, either by tillage or fertilizer deep-banding, but best-fit Cmin values for field conditions without soil disturbance (no-till with surface-broadcast fertilizer) were 2.5 to 3 times greater than baseline values. These results indicate current model limitations in modeling undisturbed (no-till) field management conditions, and caution that models calibrated for fields or watersheds predominated by tilled soil conditions may not function equally well in testing management scenarios without tillage.
  • Authors:
    • Humburg, D. S.
    • Schumacher, T. E.
    • Osborne, S. L.
  • Source: Agricultural Journal
  • Volume: 3
  • Issue: 5
  • Year: 2008
  • Summary: Although no-till soil management has many benefits, including protecting the soil from erosion, improving soil organic matter and improving soil moisture storage, depending on environmental conditions there could be a number of potential problems. Implementation of no-till soil management in eastern South Dakota can lead to wet and cold soils at the time of planting. Cover crops have the potential to utilize excess soil moisture and improve soil conditions at planting. A field experiment was established to evaluate the impact of 14 different cover crop species as well as no cover crop and conventional tillage on soil conditions prior to corn planting and the impact on corn yield and quality. The experimental design was a randomized complete block design with 4 replications. Cover crops evaluated include a mixture of grass, legumes, cool and warm season crops. All cover crops were planted in early August (following spring wheat harvest) at recommended seeding rates. The following spring all plots were planted to corn ( Zea mays L.). The experiment was conducted in a 3 year crop rotation (soybean [ Glycine max (L.) Merrill]/spring wheat ( Triticum aestivum L.)-cover crop/corn). Cover crop species that survived the winter included hairy vetch, red clover, sweet clover, Alsike clover, slender wheatgrass and winter ryegrass. The presence of these species increased soil strength and reduced soil moisture. Corn grown following hairy vetch was the only treatment that exhibited a significant reduction in plant population. Corn yield for plots grown under red clover, winter ryegrass and no cover crop had yield significantly higher than corn grown after conventional tillage, hairy vetch and slender wheatgrass. This experiment illustrated the ability of cover crops to utilize excess soil moisture and increase soil strength compared to conventional tillage or no cover crop.
  • Authors:
    • Miller, P. S.
    • Karthikeyan, K. G.
    • Panuska, J. C.
  • Source: Geoderma
  • Volume: 145
  • Issue: 3-4
  • Year: 2008
  • Summary: The impact of field surface conditions and erosion processes on runoff volume, soil loss and sediment particle size during the rainfall runoff period was investigated. Results are reported for multiple events and from within individual events (intra-event) for sites with different corn (Zea mays L.) management systems (i.e., grain (CG), silage (CS), and silage-manure (CSM)). The multi-event bulk runoff volume and soil loss for CG were less than that for CS and CSM due to higher residue levels increasing surface roughness, ponding and infiltration. The aggregate stability for CG treatment was greater than that for CS and CSM and aggregate size peaks were identified at 5.4, 32,160 and 570 pm. Size peaks at 32 and 570 pm had the highest combined frequency (64%). Intra-event continuous monitoring covered silage plots with crop-rows oriented up-and-down the slope (CS) and along the contour (CScont). The crop-row orientation significantly influenced both runoff and sediment loss (concentration, load, size-distribution) patterns. The runoff volume and sediment concentration for CS was twice that of CScont. While no treatment difference attributable to residue coverage was evident for particle-size dynamics, crop-row orientation had a significant effect with finer-sized particles exported from the contoured site. Surface sealing, more pronounced at the silage sites, occurred after the 1st major storm in a season for all monitoring periods, types, and treatments, and it significantly influenced runoff generation, sediment load, and size distribution characteristics. Under crusted conditions, a storm with slightly higher rainfall depth but significant lower erosive potential, generated 53% more runoff and twice as much sediment compared to an early-season event. During crust development finer particles dominated sediment composition, later shifting to larger particles due to rill erosion once a stable crust was established. These results are expected to improve our understanding and, hence, predictive capability for transport of particulate-bound contaminants from row-crop systems, especially under conditions promoting surface crust formation. (c) 2008 Elsevier B.V. All rights reserved.
  • Authors:
    • Cassman, K. G.
    • Specht, J. E.
    • Weiss, A.
    • Setiyono, T. D.
    • Dobermann, A.
  • Source: Field Crops Research
  • Volume: 108
  • Issue: 1
  • Year: 2008
  • Summary: Different approaches have been used to simulate leaf area index (LAI) in soybean ( Glycine max L. Merr). Many of these approaches require genotype-specific calibration procedures. Studies modeling LAI dynamics under optimal growth conditions with yields close to the yield potential of soybean have remained scarce. A sink-driven approach was developed and evaluated for LAI simulation in soybean under near-optimal environments. The rate of change in expanding leaf area was simulated using the first derivative of a logistic function accounting for plant population density, air temperature, and water deficit. The rate of change in senescing leaf area was also simulated using the first derivative of a logistic function, assuming monocarpic senescence that began at the flowering stage (R1). Phenology was simulated as a function of temperature and photoperiod. Data for model development and evaluation were obtained from irrigated field experiments conducted at two locations in Nebraska, where agronomic management was optimized to achieve growth at a near yield potential level. LAI simulation with the proposed model had average RMSE of 0.52 m 2 m -2 for independent data at the two locations. The proposed model has minimum input requirements. Interactions between leaf growth and source-driven processes can be incorporated in the future, while maintaining the basic physiological assumptions underlining leaf expansion and senescence.
  • Authors:
    • Wilhelm, W. W.
    • Varvel, G. E.
  • Source: Agronomy Journal
  • Volume: 100
  • Issue: 4
  • Year: 2008
  • Summary: Proposals promoting the use of massive amounts of crop residues and other lignocellulosic biomass for biofuel production have increased the need for evaluation of the sustainability of cropping practices and their effect on environment quality. Our objective was to evaluate the effects of crop rotation and N fertilizer management and their stover production characteristics on soil organic carbon (SOC) levels in a long-term high-yielding irrigated study in the western Corn Belt. An irrigated monoculture corn ( Zea mays L.), monoculture soybean [ Glycine max (L.) Merr.], and soybean-corn cropping systems study was initiated in 1991 on a uniform site in the Platte Valley near Shelton, NE. Soil samples were collected in 1991 before initiation of the study and in the spring of 2005 and analyzed for SOC. Significant differences in total SOC values were obtained between rotations and N rates at the 0- to 7.5- and 0- to 15-cm depths in 2005 and all total SOC values were equal to or greater than SOC values obtained in 1991. Residue production was greater than 6 Mg ha -1, a level that appears to be sufficient to maintain SOC levels, in all systems. Can residue amounts above this level be harvested sustainably for biofuel production in cropping systems similar to these? Though these results suggest that a portion of corn stover could be harvested without reducing SOC under the conditions of this investigation, the direct impact of stover removal remains to be evaluated.
  • Authors:
    • Zhu, D. W.
    • Jin, Z. Q.
  • Source: Acta Agronomica Sinica
  • Volume: 34
  • Issue: 9
  • Year: 2008
  • Summary: Nine scenarios of climatic change and climatic variability were generated in 19 sites in 3 agroecological zones in northeast China using the WGEN as a tool and based on the output of three general circulation models (GISS, GFDL, and UKMO GCMs), the local current daily weather data from 1961 to 2000 at each site, as well as on the three hypotheses on the increase in climatic variability in future. Four crop models (SOYGRO, CERES-Maize, CERES-Wheat, and CERES-Rice) were selected as the effect models and their parameter modification, validation and sensitivity analyses were carried out using the baseline weather, statistical yield data of the 4 crops and the local typical soil data. Finally, the potential impacts of changes in both climate and its variability on the food production in this regions with a doubling of CO 2 concentration doubled were assessed by running the effect models under both baseline and various (climatic change+climatic change variability) scenarios, and by comparing the outputs simulated. The results showed that the four effect models were available in the studied regions and can be used as a tool in climate impact study. Climate change would be favorable for soyabean and rice production in the region, especially in the northern cold zone and eastern wet zone, but unfavorable for both maize and spring wheat, where the simulated yields particularly maize yield, were significantly reduced under all the scenarios. With increasing of climatic variability, not only the yields were reduced compared with the control, but also the yield stabilities also decreased for the rainfed crops, such as soyabean, maize and spring wheat. However, there was no influence for the irrigated rice.
  • Authors:
    • Santini, J. B.
    • Vyn, T. J.
    • Faghihi, J.
    • Ferris, V. R.
    • Westphal, A.
    • Creech, J. E.
    • Johnson, W. G.
  • Source: Weed Science
  • Volume: 56
  • Issue: 1
  • Year: 2008
  • Summary: Certain winter annual weeds have been documented as alternative hosts to soybean cyst nematode (SCN), and infestations of such species have become common in no-till production fields in the Midwest. This research was conducted to determine the influence of herbicide- and cover-crop-based winter annual weed management systems and crop rotation on winter annual weed growth and seed production, SCN population density, and crop yield. Two crop rotations (continuous soyabean and soyabean-maize) and six winter annual weed management systems (a nontreated control, autumn and spring herbicide applications, spring-applied herbicide, autumn-applied herbicide, autumn-sown annual ryegrass, and autumn-sown winter wheat) were evaluated in no-tillage systems from autumn 2003 to 2006 at West Lafayette and Vincennes, Indiana. Autumn or spring herbicide treatments generally resulted in lower winter annual weed densities than cover crops. Densities of henbit and purple deadnettle increased over years in the cover crop systems but remained constant in the herbicide systems. Averaged over sites and years, winter annual weed densities were nearly 45% lower in the spring than the autumn due to winter mortality. Maize yield was reduced by the cover crops at West Lafayette but not Vincennes. Winter annual weed management system had no influence on soyabean yield. SCN population density was reduced by including maize in the crop sequence but was not influenced by winter annual weed management. The density of weedy host species of SCN in the experimental area was relatively low (less than 75 plants m -2) compared to densities that can be observed in production fields. The results suggest that inclusion of maize into a cropping sequence is a much more valuable SCN management tool than winter annual weed management. In addition, control of winter annual weeds, specifically for SCN management, may not be warranted in fields with low weed density.
  • Authors:
    • Egli, D. B.
  • Source: Field Crops Research
  • Volume: 106
  • Issue: 1
  • Year: 2008
  • Summary: The increases in crop yield that played an important role in maintaining adequate food supplies in the past may not continue in the future. Soybean ( Glycine max L. Merrill) county yield trends (1972-2003) were examined for evidence of plateaus using data (National Agricultural Statistics Service) for 162 counties (215 data sets) in six production systems [Iowa, Nebraska (irrigated and non-irrigated), Kentucky and Arkansas (irrigated and non-irrigated)] representing a range in yield potential. Average yield (1999-2003) was highest in irrigated production in Nebraska (3403 kg ha -1) and lowest in non-irrigated areas in Arkansas (1482 kg ha -1). Average yield in the highest yielding county in each system was 31-88% higher than the lowest. Linear regression of yield versus time was significant ( P=0.05) in 169 data sets and a linear-plateau model reached convergence (with the intersection point in the mid-1990s) in 35 of these data sets, but it was significantly ( P=0.10) better in only three data sets (
  • Authors:
    • Basnyat, P.
    • Huber, D.
    • Fernandez, M. R.
    • Zentner, R. P.
  • Source: Soil & Tillage Research
  • Volume: 100
  • Issue: 1-2
  • Year: 2008
  • Summary: Fusarium head blight (FHB) is an important disease which has been causing damage to wheat and barley crops in western Canada. Because crop residues are an important source of inoculum, it is important to know the ability of Fusarium spp. to colonize and survive in different residue types, and how their populations might be affected by agronomic practices. Sampling of residue types on producers' fields for quantification of Fusarium and other fungi was conducted in 2000-2001 in eastern Saskatchewan. Fusarium spp. were isolated from most fields, whereas their mean percentage isolation (MPI) was over 50% for cereal and pulse residues, and under 30% for oilseed residues. The most common Fusarium, F. avenaceum, had a higher MPI in pulse and flax (45-48%) than in cereal or canola (10-22%) residues. This was followed by F. equiseti, F. acuminatum, F. graminearum, F. culmorum and F. poae which were isolated from all, or most, residue types. Factors affecting Fusarium abundance in residues included the current crop, cropping history, and tillage system. In cereal residues, the MPI of F. avenaceum was higher when the current crop was another cereal (24%) versus a noncereal (4-8%). When the current crop was another cereal, the lowest MPI of F. avenaceum and F. culmorum occurred when the field had been in summerfallow (SF) two years previous (F. avenaceum: 17% for SF, 28% for a crop; F. culmorum: 1% for SF, 4% for a crop); in contrast, F. equiseti and Cochliobolus sativus were most common in residues of cereal crops preceded by SF (F. equiseti: 16% for SF, 10% for a crop; C. sativus: 22% for SF, 13% for a crop). The MPI of F graminearum was higher when the crop two years previous was an oilseed (7%) versus a cereal (4%). In regards to tillage effects, when the current crop was a cereal, the MPI of F. avenaceum was higher under minimum (MT) and zero tillage (ZT) (22-37%) than conventional tillage (CT) (15%), that of F. graminearum was lowest under ZT (3% for ZT, 7-11% for CT-MT), whereas that of C. sativus was highest under CT (27% for CT, 6-11% for MT-ZT). Under ZT, previous glyphosate applications were correlated positively with F. avenaceum and negatively with F. equiseti and C. sativus. These observations generally agreed with results from previous FHB and root rot studies of wheat and barley in the same region. Percentage isolation of F avenaceum from noncereal and of F. graminearum from cereal residues were positively correlated with FHB severity and percentage Fusarium-damaged kernels of barley and wheat caused by the same fungi. Crown Copyright (C) 2008 Published by Elsevier B.V. All rights reserved.